Ignition triggering circuit with automatic advance

ABSTRACT

In a breakerless ignition system for a spark ignited engine, two separate magnets are used for generating the electrical energy supplied to the spark plug and for generating triggering signals applied to an electronic switch controlling the application of electrical energy to the spark plug. The system is a condenser discharge system wherein a main rotating magnet assembly generates a varying voltage in a generating coil positioned adjacent its path of movement. A condenser is connected with the generating coil through a rectifying means so as to be charged when the voltage induced in the generating coil is of one polarity. A silicon controlled rectifier controls the discharge of the condenser through the primary of a step-up transformer having its secondary winding connected to the spark plug. Triggering signals for the silicon controlled rectifier are provided by a separate stationary triggering magnet and coil assembly. A rotating piece of magnetic material moves past the triggering magnet and coil assembly to induce a triggering voltage in the triggering coil, the magnitude of which at different positions of the rotating piece is dependent on the speed of rotation so that at different engine speeds the triggering level of voltage is obtained at different positions of the rotating part to provide an automatic spark advance.

United States Patent [191 Burson et al.

[111* 3,809,040 [451 May 7,1974

[ IGNITION TRIGGERING CIRCUIT WITH AUTOMATIC ADVANCE [75] Inventors: Bob 0. Burson, East Longmeadow; Russell Dale Phelon, Longmeadow, both of Mass.

[73] Assignee: R. E. Phelon Company, Inc., East Longmeadow, Mass.

[22] Filed: June 5, 1970 [21] Appl. No.: 43,845

Related U.S. Application Data [63] Continuation-impart of Ser. No. 758,563, Sept. 9,

1968, abandoned.

Primary ExaminerLaurence M. Goodridge I Attorney, Agent, or FirmMcCormick, Paulding & l-luber 7] 1 ABSTRACT In a breakerless ignition system for a spark ignited engine, two separate magnets are used for generating the electrical energy supplied to the spark plug and for generating triggering signals applied to an electronic switch controlling the application of electrical energy to the spark plug. The system is a condenser discharge system wherein a main rotating magnet assembly generates a varying voltage in a generating coil positioned adjacent its path of movement. A condenser is connected withv the generating coil through a rectifying means so as to be charged when the voltage induced in the generating coil is of one polarity. A silicon controlled rectifier controls the discharge of the condenser through the primary of a step-up transformer having its secondary winding connected to the spark plug. Triggering signals for the silicon controlled rectifier are provided by a separate stationary triggering magnet and coil assembly. A rotating piece of magnetic material moves past the triggering magnet and coil assembly to induce a triggering voltage in the triggering coil, the magnitude of which at different positions of the rotating piece is dependent on the speed of rotation so that at different engine speeds the triggering level of voltage is obtained at different positions of the rotating part to provide an automatic spark advance.

12 Claims, 9 Drawing Figures PATENTEDM new; 38991040 sum 1 or 3 INVENTORS BOB O. BURSON RUSSELL DALE PHELON ATTORNEYS PATENTEB MY 7 1974 TRIGGERING COIL VOLTAGE ANGLE OF ADVANCE FIG. 4

TRlGGERING LEVEL SHEET 2 OF 3 HIGH SPEED LOW SPEED FIG. 5

ROTOR POSITION PATENTEUHAY new: 1009.040 7 SHEET 3 BF 3 I l Z l I LEVEL i I TR/GGER/NG COIL I VOLTAGE I ROTOR Pas/n0 FIG.9

IGNITION TRIGGERING CIRCUIT WITH AUTOMATIC ADVANCE CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Serial No. 758,563, filed September 9, 1968 for Ignition Triggering Circuit with Automatic Advance now abandoned.

BACKGROUND OF THE INVENTION This invention relates to ignition systems for spark ignited engines of the type including a triggered electronic switch and deals'more particularly with a means for generating a triggering signal controlling the timing of the spark.

The general object of this inventionis to provide an improved breakerless ignition system having a triggering circuit of simple, reliable construction and which additionally provides for a desirable, smooth automatic advance in the timing of the spark as the speed of the engine is varied over a given range of speeds. A still further object of this invention is to provide, in a breakerless ignition system, a simple low-cost construction of means for triggering the occurrence of the spark, such means being particularly well adapted for use with condenser discharge system.

SUMMARY OF THE INVENTION The invention resides in an ignition system for a spark ignited engine wherein the application to the spark gap device of electrical energy for producing a spark is controlled by an electronic switch, such as a silicon controlled rectifier, controlled by triggering signals. These triggering signals are produced by a stationary triggering magnet and coil assembly positioned ad jacent a rotating part of the engine having an irregularity thereon which varies the reluctance of the triggering magnet flux circuit through the triggering coil as the irregularity passes the location of the triggering magnet and triggering coil. The irregularity is preferably mounted on the same part which carries a main magnet assembly used for generating the electrical power supplied to the spark gap device. In one embodiment of the invention, the irregularity is a piece of magnetic material also used as a counterweight to counterbalance such main magnet assembly in the rotating part, the rotating part having a rim of non-magnetic material in which the magnet assembly and counterweight are embedded. In another embodiment of the invention, the main magnet assembly includes two pole pieces of magnetic material, one of which in addition to serving as part of the main magnet assembly also serves as the irregularity for varying the reluctance of the triggering magnet flux path through the triggering coil. In another embodiment of the invention, the irregularity is a gap or slot formed in the rotating part which is made of magnetic material. The triggering magnet and coil assembly has two legs forming two angularly spaced pole faces, and the irregularity has length at least equal to the spacing between such pole faces. The waveform of the triggering signal may be either in the form of a voltage ramp followed by a spike, or in the form of an initial spike followed by a ramp and a subsequent spike, depending on whether the triggering coil is received on only the trailing one of said legs or on both of said legs.

BRIEF DESCRIPTION OF THE DRAWINGS rotor of FIG. 1 and indicating the manner in which the automatic advance is obtained.

FIG. 5 is a diagram illustrating different forms of advance versus speed characteristics which may be obtained for different configurations of the triggering circuit elements in a system similar to that of FIGS. 1 and 3.

FIG. 6 is a sectional view taken through a rotating part of an engine, and shows another embodiment of this invention.

FIG. 7 is a sectional view taken through a rotating part of an engine, and shows another embodiment of this invention.

FIG. 8 is a view generally similar to FIG. 2 but shows still another embodiment of this invention.

. FIG. 9 is a diagram illustrating the voltage waveforms induced in the triggering coils of FIG. 8 at different speeds of the rotor and indicating the manner in which the automatic advance is obtained.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS This invention consists of an ignition system for a spark ignited engine wherein separate means are provided for supplying electrical energy used to provide the sprak at the spark plug or other spark gap device and for generating a triggering signal used to control the timing of the occurrence of the spark. As shown herein, the means for supplying electrical energy for the spark plug is also a generating means, and eachof the separate generating means includes a part mounted on a rotating engine part rotated in Tsynchronism with the operation of the engine. Each of these ignition system parts may be mounted on separate rotating engine parts, but preferably, and as shown herein, both ignition system parts are carried by the same engine part. In FIG. 1, this engine part is shown to be a rotor 10, which may, for example, be a flywheel attached to the crankshaft or camshaft of the engine, the rotor 10 having a rim I2 of non-magnetic material, shown in section in FIG. 1, and being rotated in the direction of the arrow as the engine operates.

FIG. 1 shows the generating means used for producing the electrical energy for the spark gap device and the generating means for producing the triggering signals used to control the timing of the spark. FIG. 3, in turn, shows the remainder of the ignition system, which is connected with the generating means of FIG. 1 and with the spark gap device. Considering first FIG. 1, the generating means for producing the electrical energy used to energize the spark gap device consists of a main magnet assembly 14, embedded in the rim 12 of the rotor 10, and a stationary generating coil means 16 arranged for excitation by the main magnet assembly.

The main magnet assembly includes a permanent magnet 18 having circumferentially spaced end faces 20 and 22 of opposite magnetic polarity. Engaging these opposite end faces 20 and 22, and also embedded in the non-magnetic material of the rim 12, are two pole pieces 24 and 26 of magnetic material, preferably laminated. The pole pieces extend to the outer surface of i .the rim 12 and provide two circumferentially extending and circumferentially spaced pole opposite magnetic polarity. The generating coil means 16, which cooperates with the magnet assembly 14, includes a stator core 32 of magnetic material, preferably laminated, having two radially inwardly directed legs 34 and 36 circumferentially spaced from one another along the outer surface of the rim 12 and having arcuate pole faces 38 and 40 spaced close to the'path of movement of the magnetic pole faces 28 and 30 so that as the moving and stationary pole faces pass one another a relatively small air gap is formed therebetween. A generating coil 42 is mounted on the stator pole 34. The stator pole faces 38 faces 28 and 30 of and 40 are spaced from one another by a distance such that the leading edge 44 of the leading face 40 is spaced from the trailing edge 46 of the trailing face 38 by a distance approximately equal to the spacing between the leading edge 48 of the leading rotor face 28 and the trailing edge 50 of the trailing rotor face 30, with the circumferential extent of both the stator faces 38 and 40 being substantially less than the circumferential extent of the rotor pole faces 28 and 30. Therefore, it will be obvious that as the main magnet assembly 14 passes the generating coil means 16, the magnet 18 and its associated pole faces 28 and 30 will act to induce a magnetic flux in the stator 32 which first passes in one direction and then in the opposite direction through the coil carrying pole 34 to, in turn, induce a voltage in the generating coil 42, which is first of one polarity and then of the opposite polarity.

The means shown in FIG. 1 for generating triggering signals consists of a separate triggering-magnet and coil assembly 52, fixed relative to the stationary structure of the engine, and a flux varying irregularity carried by the rotor in the form of a piece of magnetic material 54 embedded in the rim 12. In this case, the piece 54 is located approximately diametrically opposite from the main magnet assembly 14 and serves as a counterweight for balancing the rotor against the weight of the main magnet assembly. The triggering magnet and coil I assembly 52 is located inside of the rim l2 and includes a small permanent magnet 56 having end faces 58 and 60 of opposite magnetic polarity. Associated with the magnet 52 is a stator core comprised to two pieces of magnetic material 62 and 64 which respectively engage the opposite end faces 58 and 60 of the magnet and which extend radially inwardly from the magnet toward the rim 12 to provide two circumferentially spaced stator poles or legs 66 and 78. A triggering coil 80 is mounted on the stator leg 78, and the two poles 66 and 78 have end faces 82 and 84 located in a common circle concentric with the axis of rotation of the rotor 10, and circumferentially-spaced from one another.

For cooperation with the stator end faces 82 and 84 of the triggering magnet and coil assembly, the magnetic piece or counterweight 54 includes a pole face 86 located on the inner surface of the rim 12 and arranged so as to pass the stator pole faces 82 and 84 with a small air gap in between. The spacing between the leading and trailing edges of the rotor pole face 86 is approximately equal tothe spacing between the leading edge of the leading stator face 82 and the trailing edge of the trailing stator face 84 so that at least one position of the rotor, the rotor face 86 overlaps both of the stator faces 82 and 84.

From a consideration of FIGS. 1 and 2, it will be obvious that as the rotor 10 rotates, the magnetic piece 54 in the rim 12 serves to vary the reluctance of the flux circuit of the triggering magnet 56 through the triggering coil to induce a varying voltage in the triggering coil. FIG. 1 shows the position of the rotor just as the leading edge of the rotor face 86 comes into alignment with the leading stator face 82. Prior to the reaching of this position, the flux through the triggering coil is substantially constant and no voltage is induced therein. However, as the FIG. 1 position is reached, the leakage pattern of the flux path is changed and a greater amount of flux flows through the triggering coil 80. As the rotor face 86 advances over the pole face 82, the reluctance of the flux path still further decreases, primarily as a result of'increasing leakage, until the rotor face 86 overlaps both of the stator faces 82 and 84. At this point, the reluctance of the flux path through the triggering coil 80 is rapidly reduced as a result of the flux path passing directly through the stator pieces 62 and 64 and the rotor piece 54 with little leakage. The net effect of this is that the voltage waveform induced in the triggering coil 80 consists of. a ramp portion which occurs throughout the time the rotor moves from the position of FIG. 1 to the position of FIG. 2 followed by a spike initiated approximately at the rotor position of FIG. 2 at which both of the stator pole faces start to move onto the rotor pole face 86. After the rotor moves beyond the position shown in FIG. 2 and the pole face 82 moves off of the rotor face 86, the reluctance of the flux path through the triggering coil 80 again decreases and a voltage of opposite polarity is induced therein. The magnitude of the ramp voltage induced in the triggering coil 80 as the rotor moves from the FIG. 1 to the FIG. 2 position depends on the speed of the rotor so that the voltage signal from the triggering coil may be used to provide an automatic advance, as explained in more detail hereinafter in connection with FIG. 4.

FIG. 3 is an electrical shcematic diagram showing the portion of the ignition system connected between the generating coil 42 and triggering coil 80 and the spark gap device. The spark gap device is shown at 88 in FIG. 3 and may be a conventional spark plug. The circuit of FIG. 3 is of the type referred to as a condenser discharge system, and includes a condenser 90 connected with the generating coil 42 through a rectifier means, consisting of two diodes 92 and 94, so that the condenser 90 is charged when the voltage induced in the generating coil 42 is of one polarity. That is, as the main magnet assembly 14 passes the generating coil means 16, a voltage waveform is induced in the generating coil 42 which is first'of one polarity and then of the other polarity, and only that portion of the wave which is of one polarity is used to charge the condenser. The condenser 90 is, in turn, connected with the primary coil 96 of a step-up transformer having its secondary coil 98 connected in series with the spark plug 88. In the circuit between the condenser 90 and the primary winding 96 is an electronic switch consisting of a silicon controlled rectifier 100 having its anode and cathode terminals connected in series with the condenser and the primary winding. The triggering coil 80 controls the conduction of the silicon controlled rectifier 100 and is connected between the triggering tenninal and the cathode of the silicon controlled rectifier.

In the normal operation of the system shown in FIGS. 1 and 3, the main magnet assembly 14 first passes the generating coil means 16 and induces the voltage in the generating coil 42'which charges the condenser 90. After a charge is built up on the condenser 90, it is initially prevented from passing to the primary winding 96 of the step-up transformer by the silicon controlled rectifier 90 which is at that time in a non-conducting state. Sometime after the main magnet assembly 14 passes the generating coil assembly 16, however, the rotor face 86 provided by the counterweight 54 moves past the stator faces 82 and 84 of the triggering magnet and coil assembly and induces a triggering voltage in the triggering coil 80 which switches the silicon controlled rectifier to a conducting state, thereby discharging the condenser 90 through the primary winding 96 of the step-up transformer and inducing a high potential in'the secondary winding 98 to causethe occurrence of a spark at the spark plug 88. As the pole face 86 of the magnetic piece 54 moves away from the pole faces 82 and 84 of the triggering magnet andcoil assembly, a reverse voltage is induced in the triggering coil 80 and a reverse voltage is applied across the anode and cathode terminals of the silicon controlled rectifier, as a result of resonance between the condenser 90 and winding 96, to positively switch the silicon controlled rectifier to a non-conducting state, thereby conditioning it for operation on the following cycle.

As mentioned, the voltage waveform induced in the triggering coil 80 is one which, in conjunction with the silicon controlled rectifier 100, operates to produce an automatic advance in the timing of the occurrence of the spark in response to changes in the speed of the rotor and the associated engine. Referring to FIG. 4, the lines 102, 104 and 106 indicate generally the shape of a voltage waveform induced in the triggering coil 80 at different speeds of the rotor 10. The horizontal line 108 indicates the level of voltage required to obtain switching of the silicon controlled rectifier from its non-conducting state to its conducting state. The rotor position A corresponds generally to the position shown in FIG. 1 at which the leading edge of the rotor pole face 86 starts to move over the leading stator pole face 82. The rotor position C represents generally the rotor position shown in FIG. 2 at which the leading edge of the rotor pole face starts to move over the trailing'stator pole face 84.

The line 102 in the FIG. 4 is the voltage waveform obtained at a low speed of the rotor, and it will be noted that at this low speed the voltage induced in the triggering coil does not rise above the triggering level 108 throughout the ramp portion located between the rotor positions A and C. At the rotor position C, however, a spike occurs in the waveform-which carries the voltage above the triggering level so that firing occurs at approximately this rotor position. At all speeds below that represented by the line 102, triggering and firing of the spark plug is produced by the spike portion of the waveform which always occurs at approximately the rotor position C. Therefore, over a given range of low engine speeds firing will always occur at approximately the same rotor position.

The line 104 in FIG. 4 represents the voltage waveform induced'in the triggering coil at an intermediate speed, and from this line, it will be noted that it crosses the triggering level 108 at a rotor position B, switching of the silicon controlled rectifier and-firing of the spark plug therefore occurring at this rotor position. The line 106 of FIG. 4 represents the waveform induced in the triggering coil 80 at a relatively high speed, and in this waveform all of its ramp portion is located above a triggering level 108. However, it should be noted that as the leading edge of the rotor face 86 moves onto the leading stator pole face 82, a short initial rapid change in the reluctance of the flux path through the triggering coil 80 is produced, which produces a sharp rise in voltage preceding the ramp portion, this sharp rise being indicated at 110 in FIG. 4 in connection with the line 106. Therefore, at relatively high speeds, triggering occurs at the point where the initial steep rise portion of the voltage waveform crosses the triggering level 108, the rotor position at which this firing occurs being at approximately the rotor position A for all speeds higher than that represented by the line 106.

The overall result produced by the triggering means, explained above in connection with FIG. 4, is that at relatively low speeds of the rotor and engine, firing occurs at or near the rotor position C, which may, for example, correspond to approximately the top deadcenter position of the piston associated with the spark plug 88. After this given range of low speeds is passed, an intermediate range of speeds is entered throughout which the timing of the spark is advanced as the speed is increased the advancing of the timing increasing with speed until firing occurs at the rotor position A. After the rotor speed is increased to the point where firing occurs at the rotor position A, further increases .in speed affect substantially no change in the timing of the spark with the spark occurring at all such higher speeds at approximately the rotor position A.

The solid line 112 of FIG. 5 indicates the manner in which the timing of the spark is advanced in response to the rotor speed as explained above. Thatis, throughout a low range of speeds from zero to D, the firing oc-' curs at substantially a zero or very low angle of advance. At speeds between D and E, the angle of advance increases substantially linearly with increases in the rotor speed and at speeds in excess of E, the angle of advance remains approximately constant. It should also be noted that by changing the physical characteristics of the rotor face 86 and of the triggering magnet and coil assembly, different characteristics of angle of advance versus rotorspeed may be obtained. For example, the length of the spacing between the stator pole faces 82 and 84 determines the length of the ramp portions of the voltage curves shown in FIG. 4. The slope of the ramp portions of these curves may, in turn, be varied by varying the shape or orientation of the stator poles 66 and 70, by changing the strength of the magnet 56, or by changing the number of turns of winding of the triggering coil 80.

Therefore, as indicated in FIG. 5, a system providing for a greater amount of advance, as indicated by the line 114, may be obtained by increasing the spacing between the stator pole faces. Alternatively, a system having approximately the same amount of advance as that represented by the line 112, but in which the advance occurs over a smaller range of rotor speeds, may be obtained by increasing the steepness of the ramp portions of FIG. 4, as by increasing the number of turns of winding on the coil 80, the characteristic of such a system being illustrated by the line 116 of FIG. 5. The line 118 of FIG. illustrates the characteristic of a system having substantially the same amount of advance as the system represented by the line 1 12 but wherein the advance occurs over a greater range of rotor speeds as a result of the ramp portions of FIG. 4 having a lesser degree of steepness, as a result, for example, of the coil 80 having a smaller number of turns. From FIG. 5, it

will therefore be obvious that almost any desired form of advance versus rotor speed characteristic may be obtained by properly designing the elements of the triggering signal generating means.

In the embodiment of the invention above described, a separate magnetic piece or counterweight 54 is used as an irregularity forvarying the flux through the triggering coil 80. The use of this piece for per forming the flux varying function is, however, not necessary, and if desired, the leading pole piece 24 of the main magnet assembly 14 may be used for this purpose. The broken lines of FIG. 1 illustrate a triggering magnet and coil assembly positioned to make use of the leading pole face 24 as the flux varying element. In this broken line illustration, the parts have been given the same reference numbers as in the full line representation except for having the suffix 0 added thereto. In this case, the magnet and triggering coil assembly 52a is located on the outside of the rotor rim l2 similarly to the generating coil means 16, and is further so arranged that the stator pole faces 82a and 84a are located close to'the path of movement of the rotor or magnet pole faces 28 and 30. The spacing between the leading edge of the leading stator pole face 84a and the trailing edge of the trailing stator pole-face 82a is approximately equal to the spacing between the leading and trailing edges of the rotor pole face 28. Therefore, it will be obvious that as the pole piece 24 is rotated past the magnet and pole assembly 52a, a voltage is induced in the triggering coil 80a in the same manner as described above in connection with the movement of the rotor pole face 86 past the triggering magnet and coil assembly 52.

In the previously described embodiments of the invention, the irregularity for varying the flux through the magnet and coil assembly has consisted of a piece of magnetic material embedded in the non-magnetic material of the rotor rim. Obviously, however, the irregularity may take many other different forms. For example, FIG. 6 shows a triggering magnet and coil assembly 120 which is generally similar to the triggering magnet and coil assembly 52 of FIG. 1 except for the two pieces of magnetic materiall22 and 124 which make up the stator core being comprised of straight pieces of material rather than pieces that are bent as are the pieces 62 and 64 of FIG. 1. The triggering magnet and coil assembly 120 in addition to the two stator pieces 122 and 124 includes a permanent magnet 126 and a coil 128 received on the trailing leg of the stator core as provided by the piece 122. The triggering magnet and coil assembly 120 is located adjacent a rotating part 130 of the engine which is made of a magnetic material and which, for example, may be the shaft to which the flywheel of the engine is connected. The direction of rotation of the part 130 is shown by the arrow in FIG. 6. The irregularity which cooperates with the triggering magnet and coil assembly 120 is a raised protuberance 132 having a' circumferential length at least approximately equal to the circumferential spacing between the leading edge of the leading piece 124 of the stator core and the trailing edge of the trailing piece 122 of the stator core. Therefore, it will be obvious that the effect of the irregularity 132 in inducing a voltage in the coil 128 is similar to the effect of the counterweight 54 in inducing a voltage in the triggering coil of FIG. 1.

FIG. 7 shows another form of irregularity which may be used in practicing this invention. In this figure, the

triggering magnet and coil assembly is indicated at and is identical with that shown in FIG. 6. This triggering magnet and coil assembly, in the FIG. 7 arrangement, is located adjacent a rotating part 134 which is made of a magnetic material and which again may, for example, be the shaft of the engine to which the flywheel is attached. To provide a flux varying irregularity for cooperation with the triggering magnet and coil assembly 120, the part 134 has formed therein a slot or gap 136 which moves past the triggering magnet and coil assembly during each revolution of the part 134', the part 134 being normally rotated in the direction of the arrow. The affect of the gap 136 on the flux through the triggering magnet and coil assembly 120 of FIG. 7 is substantially the reverse of the affect of the protuberance 132 of FIG. 6 on the flux through the triggering magnet and coil assembly of FIG. 6. That is, as the gap 136 of FIG. 7 approaches the triggering magnet and coil assembly, the flux through such assembly is reduced rather than increased. However, the rate of change of the flux, and consequently the voltage waveform induced in the triggering coil 128 of FIG. 7, will be the same as that of FIG. 6, the length of the gap 136 in the circumferential direction being at least as long as the circumferential spacing between the leading edge of the leading piece'l24 and the trailing edge of the trailing piece 122.

In connection with all of the previously described embodiments of the invention, it should be understood that the circumferential length of the irregularity used with the triggering magnet and coil assembly may be greater than the length between the poles of the triggering magnet and coil assembly without affecting that portion of the signal induced in the triggering coil used to effect triggering of the ignition system. The important consideration is that the circumferential length of the irregularity be at least approximately equal to the spacing between the leading edge of the leading stator pole and the trailing edge of the trailing stator pole so that at one position of the rotor the leading stator pole overlaps the irregularity and remains overlapped therewith until reaching a second rotor position at which both stator'poles are simultaneously overlapped with the irregularity. Of course, if the spacing between the stator poles is increased to increase the angle of advance, the irregularity must be of such a circumferential length as to accommodate such increased spacing.

In all of the preceding embodiments of the invention, the triggering coil of the triggering magnet and coil assembly has consisted of a single coil placed on the trailing pole or leg of the stator core. This causes to be induced in the triggering coil a voltage waveform similar to that shown in FIG. 4 consisting essentially of an initial gradually rising ramp portion followed by a sharply rising spike. This, as previously mentioned, provides a variable advance during intermediate speeds of the engine at which triggering is effected by the ramp portion of the voltage waveform which reaches the triggering level at different rotor positions for different rotor speeds. If desired, the triggering magnet and coil assembly may also be constructed so as to provide for a simple two-step type of advance wherein the firing occurs at one rotor position for low rotor speeds and at another rotor position for higher rotor speeds with no intermediate degrees of advance. This is accomplished by constructing the triggering coil of two separate coils or coil segments and by placing them individually on the two stator poles and connecting them in series aiding relationship. Such an arrangement is shown in FIG. 8 wherein the rotating part is indicated at 138 and carries a counterweight 140 of magnetic material, the part 138 being similar to the rotor of FIG. 1. The triggering magnet and coil assembly is indicated at 142 and consists of a magnet 144 and two stator pieces 146 and 148. Received on the stator piece 146 is a coil 150 forming one part of the triggering coil and similarly received on the stator piece 148 is another coil 52 forming another part of the triggering coil. The two coils 150 and 152 are connected in series aiding relationship, and in the ignition system of FIG. 3, for example, may replace the single coil 80 therein illustrated. The part 138 in FIG. 8 rotates in the direction of the arrow.

FIG. 9 shows the triggering signal developed across the two series connected coils 150 and 152 of FIG. 8 as the counterweight 140 moves therepast at different speeds. More particularly, considering the low speed waveform 154, as the pole face provided by the counterweight 140 moves toward the leading stator piece 148 there is a rather rapid increase in the leakage flux which passes through the leading triggering coil 152 but which does not pass through the trailing triggering coil 150. This produces an initial spike 156 in the voltage waveform which occurs at the illustrated rotor position A, the rotor position A, as in FIG. 4, being the position at which the pole face of the counterweight 140 starts to move into overlapped relationship with the stator pole provided by the stator piece 148. Following the initial spike 156, a gradual increase in the leakage flux through both the triggering coils 152 and 150 produces a ramp shaped portion 158 of the voltage waveform which, at the rotor position C, is followed by a sharply rising spike 160 occurring when both of the pole pieces 146 and 148 of the triggering magnet and coil assembly move simultaneously into overlapped relationship with the pole face provided by the counterweight 140.

As will be evident from FIG. 9, at the low rotor speeds the triggering signal does not rise to the triggering level until the rotor reaches the position C at which the terminal spike 160 is induced in the triggering coils. Therefore, at all low speeds of the engine firing occurs at the rotor position C. At higher speeds of the engine, as represented by the higher speed waveform 162 of FIG. 9, the initial spike produced in the waveform at the rotor position A exceeds the triggering level so that at such higher speeds the triggering occurs at the rotor position A rather than the rotor position C.

We claim:

1. A trigger signal producing means for use in a breakerless ignition system for a spark ignited engine having at least one spark gap device and a part rotated in synchronism with the operation thereof, and which ignition system includes a triggered electronic switch the triggering of which determines the timing of the firing of said at least one spark gap device, said trigger signal producing means comprising means defining a flux varying irregularity carried by said rotatable part of said engine for rotation therewith, and a stationary triggering magnet and coil assembly located adjacent the path of said flux varying irregularity, said triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two pole faces comprising opposite ends, of a low reluctance path passing through said coil for the flux of said triggering magnet, said two pole faces of said triggering magnet and coil assembly being located close to and facing the path of said flux varying irregularity and being spaced from one another circumferentially of said path so that as said rotatable part is rotated said flux varying irregularity varies the amount of flux from said triggering magnet passing through said triggering coil, and said flux varying irregularity having a circumferential length at least approximately as great as the circumferential spacing between the leading edge of the leading one of said two pole faces and the trailing edge of the trailing one of said two pole faces and being continuous along said circumference length thereof so that as said irregularity is moved toward and past said triggering magnet and coil assembly by the rotation of said rotatable part said leading one of said two pole faces first overlaps said irregularity and then remains overlapped with said irregularity until after said trailing pole face subsequently overlaps said irregularity simultaneously with said leading pole face.

2. A trigger signal producing means as defined in claim 1 further characterized by said flux varying irregularity comprising a pole face defined by a quantity .of magnetic material.

3. A trigger signal producing means as defined in claim 1 for use in a breakerless ignition system for a spark ignited engine wherein said part rotated in synchronism with the operation of said engine is a rotor with a rim of non-magnetic material having embedded therein a single'permanent magnet assembly cooperable with a stator assembly for producing power for said ignition system, further'characterized by said flux varying irregularity comprising a pole face on said rotor rim defined by a counterweight of magnetic material embedded in said rim at a location generally diametrically opposite from said permanent magnet assembly so as to balance said rotor.

4. A trigger signal producing means as defined in claim 1 for use in a breakerless ignition system for a spark ignited engine wherein said part rotated in synchronism with the operation of said engine is a rotor with a rim of non-magnetic material having embedded therein a permanent magnet assembly cooperable with a stator assembly for producing power for said ignition system and which permanent magnet assembly includes two pole pieces of magnetic material defining two circumferentially extending and circumferentially spaced rotor pole faces, further characterized by said flux varying irregularity consisting of one of said rotor pole faces.

claim 1 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote from said triggering magnet,said triggering coil being mounted on at least one of said two pieces of magnetic material.

7. A trigger signal producing means as defined in claim '6 further characterized by said triggering coil consisting of a single coil mounted on the trailing one of said two pieces of magnetic material.

8. A trigger signal producing means as defined in claim 6 further characterized by said triggering coil consisting of two separate coils each mounted on a respectively associated one of said two pieces of magnetic material and electrically connected to one another in series aiding relationship.

' 9. In a breakerless ignition system for a spark ignited engine having at least one spark gap ignition device and a part rotatable in synchronism with the operation thereof, the combination comprising a triggered electronic switch the triggering of which determines the timing of the firing of said at least one spark gap device, said triggered electronic switch having a triggering terminal and being triggered when the voltage applied to said triggering terminal rises from a low value to a given higher triggering level, and a trigger signal producing means connected with said triggering terminal for supplying triggering signals thereto, said trigger signal producing means including a flux varying irregularity carried by said rotatable partof said engine for rotation therewith, and a stationary triggering magnet and coil assembly located adjacent the path of said flux varying irregularity, said triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two pole faces comprising opposite ends of a low reluctance flux path passing through said coil for the flux of said triggering magnet, said two pole faces of said triggering magnet and coil assembly being located close to and facing the path of said flux varying irregularity and being spaced from one another circumferentially of said path so that as said rotatable. part is rotated said flux'varying irregularity varies the amount of flux from said triggering magnet passing through said triggering coil, said flux varying irregularity having a circumferential length at least approximately as great as the circumferential spacing between the leading edge of the leading one of said two pole faces and the trailing edge of the trailing one of said two pole faces and being continuous along said circumference length thereof so that as said irregularity is moved toward and past said triggering magnet and coil assembly by the rotation of said rotatable part said leading one of said two pole faces first overlaps said irregularity and then during a given number of degrees of subsequent rotation of said rotatable part remains overlapped with said irregularity as said trailing pole face is moved closer thereto so as to gradually change the amount of flux through said triggering coil and induce a gradually increasing voltage therein during said given number of degrees of rotation and so as to suddenly change the amount of flux through said triggering coil and induce a spike in the voltage of said triggering coil at the position of said rotatable part where said trailing pole face moves into overlapped relation with said flux varying irregularity simultaneously with said leading pole face, said triggering magnet and triggering coil being so selected that at speeds of said rotatable part corresponding to low cranking speeds of said engine the maximum value of the voltage induced in said triggering coil during said given number of degrees of rotation is less than said triggering level and the maximum value of said voltage spike is greater than said triggering level and so that at other higher speeds of said rotatable member the maximum value of the voltage induced in said triggering coil during said given number of degrees of rotation is greater than said triggering level.

10. The combination defined in claim 9 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote from said triggering magnet, said triggering coil consisting of a single coil mounted on the trailing one of said two pieces of magnetic material.

1 1. The combination defined in claim 9 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote fromsaid triggering magnet,

said triggering coil consisting of two separate coils each mounted on a respectively associated one of said two pieces of magnetic material and electrically connected to one another in series aiding relationship.

12. Means for repetitively producing ,a trigger signal for an electronically triggered ignition system for an internal combustion engine which trigger signal includes a gradual rise portion followed by a sharply rising spike portion and the steepness and maximum value of which gradual rise portion increase as the speed of said engine increases, said means comprising a part rotatable in synchronism with said engine and having an arcuate pole face defined by a quantity of magnetic material, and a stationary triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two stationary pole faces comprising opposite ends of a low reluctance path passing through said coil for the flux of said triggering magnet, said two pole faces being located close to and facing the pathof said arcuate pole face so as to form a small air gap therebetween as said arcuate pole face moves therepast so that as said rotatable part is rotated said quantity of magnetic material varies the amount of flux from said triggering magnet passing through said triggering coil, said two stationary pole faces being spaced from one another along the path of said arcuate pole face, and said arcuate pole face having a length in the direction of its path of movement at least approximately as great as the spacing between the leading edge of the leading one of said two stationary pole faces and the trailing one of said stationary pole faces said arcuate pole face being continuous along said length thereof. 

1. A trigger signal producing means for use in a breakerless ignition system for a spark ignited engine having at least one spark gap device and a part rotated in synchronism with the operation thereof, and which ignition system includes a triggered electronic switch the triggering of which determines the timing of the firing of said at least one spark gap device, said trigger signal producing means comprising means defining a flux varying irregularity carried by said rotatable part of said engine for rotation therewith, and a stationary triggering magnet and coil assembly located adjacent the path of said flux varying irregularity, said triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two pole faces comprising opposite ends of a low reluctance path passing through said coil for the flux of said triggering magnet, said two pole faces of said triggering magnet and coil assembly being located close to and facing the path of said flux varying irregularity and being spaced from one another circumferentially of said path so that as said rotatable part is rotated said flux varying irregularity varies the amount of flux from said triggering magnet passing through said triggering coil, and said flux varying irregularity having a circumferential length at least approximately as great as the circumferential spacing between the leading edge of the leading one of said two pole faces and the trailing edge of the trailing one of said two pole faces and being continuous along said circumference length thereof so that as said irregularity is moved toward and past said triggering magnet and coil assembly by the rotation of said rotatable part said leading one of said two pole faces first overlaps said irregularity and then remains overlapped with said irregularity until after said trailing pole face subsequently overlaps said irregularity simultaneously with said leading pole face.
 2. A trigger signal producing means as defined in claim 1 further characterized by said flux varying irregularity comprising a pole face defined by a quantity of magnetic material.
 3. A trigger signal producing means as defined in claim 1 for use in a breakerless ignition system for a spark ignited engine wherein said part rotated in synchronism with the operation of said engine is a rotor with a rim of non-magnetic material having embedded therein a single permanent magnet assembly cooperable with a stator assembly for producing power for said ignition system, further characterized by said flux varying irregularity comprising a pole face on said rotor rim defined by a counterweight of magnetic materIal embedded in said rim at a location generally diametrically opposite from said permanent magnet assembly so as to balance said rotor.
 4. A trigger signal producing means as defined in claim 1 for use in a breakerless ignition system for a spark ignited engine wherein said part rotated in synchronism with the operation of said engine is a rotor with a rim of non-magnetic material having embedded therein a permanent magnet assembly cooperable with a stator assembly for producing power for said ignition system and which permanent magnet assembly includes two pole pieces of magnetic material defining two circumferentially extending and circumferentially spaced rotor pole faces, further characterized by said flux varying irregularity consisting of one of said rotor pole faces.
 5. A trigger signal producing means as defined in claim 1 further characterized by said rotatable part being made of magnetic material and said flux varying irregularity comprising a gap formed in said rotatable part.
 6. A trigger signal producing means as defined in claim 1 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote from said triggering magnet, said triggering coil being mounted on at least one of said two pieces of magnetic material.
 7. A trigger signal producing means as defined in claim 6 further characterized by said triggering coil consisting of a single coil mounted on the trailing one of said two pieces of magnetic material.
 8. A trigger signal producing means as defined in claim 6 further characterized by said triggering coil consisting of two separate coils each mounted on a respectively associated one of said two pieces of magnetic material and electrically connected to one another in series aiding relationship.
 9. In a breakerless ignition system for a spark ignited engine having at least one spark gap ignition device and a part rotatable in synchronism with the operation thereof, the combination comprising a triggered electronic switch the triggering of which determines the timing of the firing of said at least one spark gap device, said triggered electronic switch having a triggering terminal and being triggered when the voltage applied to said triggering terminal rises from a low value to a given higher triggering level, and a trigger signal producing means connected with said triggering terminal for supplying triggering signals thereto, said trigger signal producing means including a flux varying irregularity carried by said rotatable part of said engine for rotation therewith, and a stationary triggering magnet and coil assembly located adjacent the path of said flux varying irregularity, said triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two pole faces comprising opposite ends of a low reluctance flux path passing through said coil for the flux of said triggering magnet, said two pole faces of said triggering magnet and coil assembly being located close to and facing the path of said flux varying irregularity and being spaced from one another circumferentially of said path so that as said rotatable part is rotated said flux varying irregularity varies the amount of flux from said triggering magnet passing through said triggering coil, said flux varying irregularity having a circumferential length at least approximately as great as the circumferential spacing between the leading edge of the leading one of said two pole faces and the trailing edge of the trailing one of said two pole faces and being continuous along said circumference length thereof so that as said irregularity is moved toward and past said triggering magnet and coil assembLy by the rotation of said rotatable part said leading one of said two pole faces first overlaps said irregularity and then during a given number of degrees of subsequent rotation of said rotatable part remains overlapped with said irregularity as said trailing pole face is moved closer thereto so as to gradually change the amount of flux through said triggering coil and induce a gradually increasing voltage therein during said given number of degrees of rotation and so as to suddenly change the amount of flux through said triggering coil and induce a spike in the voltage of said triggering coil at the position of said rotatable part where said trailing pole face moves into overlapped relation with said flux varying irregularity simultaneously with said leading pole face, said triggering magnet and triggering coil being so selected that at speeds of said rotatable part corresponding to low cranking speeds of said engine the maximum value of the voltage induced in said triggering coil during said given number of degrees of rotation is less than said triggering level and the maximum value of said voltage spike is greater than said triggering level and so that at other higher speeds of said rotatable member the maximum value of the voltage induced in said triggering coil during said given number of degrees of rotation is greater than said triggering level.
 10. The combination defined in claim 9 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote from said triggering magnet, said triggering coil consisting of a single coil mounted on the trailing one of said two pieces of magnetic material.
 11. The combination defined in claim 9 further characterized by said triggering magnet and coil assembly including two pieces of magnetic material engaging said triggering magnet at the opposite magnetic poles thereof, said two pieces of magnetic material extending from said triggering magnet toward said path of said flux varying irregularity and defining said two pole faces at their ends remote from said triggering magnet, said triggering coil consisting of two separate coils each mounted on a respectively associated one of said two pieces of magnetic material and electrically connected to one another in series aiding relationship.
 12. Means for repetitively producing a trigger signal for an electronically triggered ignition system for an internal combustion engine which trigger signal includes a gradual rise portion followed by a sharply rising spike portion and the steepness and maximum value of which gradual rise portion increase as the speed of said engine increases, said means comprising a part rotatable in synchronism with said engine and having an arcuate pole face defined by a quantity of magnetic material, and a stationary triggering magnet and coil assembly including a triggering magnet and a triggering coil fixed relative to one another and said triggering magnet and coil assembly also having two stationary pole faces comprising opposite ends of a low reluctance path passing through said coil for the flux of said triggering magnet, said two pole faces being located close to and facing the path of said arcuate pole face so as to form a small air gap therebetween as said arcuate pole face moves therepast so that as said rotatable part is rotated said quantity of magnetic material varies the amount of flux from said triggering magnet passing through said triggering coil, said two stationary pole faces being spaced from one another along the path of said arcuate pole face, and said arcuate pole face having a length in the direction of its path of movement at least approximately as great as the spacing between the leading edge of the leading one of said two stationary pole faces and the tRailing one of said stationary pole faces said arcuate pole face being continuous along said length thereof. 